He defeated Philipp Kohlschreiber 6-2, 6-2, 6-3 to level for Spain after Alexander Zverev's 6-4, 6-2, 6-2 victory over David Ferrer had given the visiting team an early lead.
Lucas Pouille got France off to a winning start in the last eight after emerging as victor in a five-set war against Italy's Andreas Seppi, who fell 6-3, 6-2, 4-6, 3-6, 6-1. However, Fabio Fognini's 6-7(6), 6-2, 6-2, 6-3 win against Jeremy Chardy tied the scoreline.
Croatia also cruised into an initial lead against Kazakhstan after world No. 3 Marin Cilic demolished 21-year-old Dmitry Popko 6-2, 6-1, 6-2, but Mikhail Kukushkin brought the Kazakhs level with a 3-6, 7-6(5), 6-4, 6-2 win over Borna Coric.
The United States won both of their quarter-final matches against Belgium, with John Isner beating Joris De Loore and Sam Querrey beating Ruben Bemelmans in Nashville, Tennessee.
Read on for a roundup of Friday's results and a look toward the upcoming quarter-final schedule.
Spain 1-1 Germany
Alexander Zverev (GER) bt. David Ferrer (ESP) 6-4, 6-2, 6-2
Rafael Nadal (ESP) bt. Philipp Kohlschreiber (GER) 6-2, 6-2, 6-3
France 1-1 Italy
Lucas Pouille (FRA) bt. Andreas Seppi (ITA) 6-3, 6-2, 4-6, 3-6, 6-1
Fabio Fognini (ITA) bt. Jeremy Chardy (FRA) 6-7(6), 6-2, 6-2, 6-3
Croatia 1-1 Kazakhstan
Marin Cilic (CRO) bt. Dmitry Popko (KAZ) 6-2, 6-1, 6-2
Mikhail Kukushkin (KAZ) bt. Borna Coric (CRO) 3-6, 7-6(5), 6-4, 6-2
United States 2-0 Belgium
John Isner (USA) bt. Joris De Loore (BEL) 6-3, 6-7(4), 7-6(8), 6-4
Sam Querrey (USA) bt. Ruben Bemelmans (BEL) 6-1, 7-6(5), 7-5
The hip injury that forced Nadal, 31, out of the Australian Open in January hasn't totally subsided, but one wouldn't have guessed it after he notched an impressive straight-sets win over Kohlschreiber on Friday.
The Spaniard's composure on clay was clear to see as he swept 34-year-old Kohlschreiber aside 6-2, 6-2, 6-3, making his injury comeback despite a lengthy Davis Cup absence, per Gracenote Olympic:
Spain needed a swift response after Zverev again demonstrated his increasing confidence at this level, beating Ferrer in three sets less than a week after falling to Isner in the final of the Miami Open.
Germany's 20-year-old prodigy already looked imperious against Australian duo Alex de Minaur and Nick Kyrgios in the first round of the World Group.
Tennis writer Jose Morgado suggested this was a new high:
Zverev's most difficult task awaits, however, as his scheduled clash against Nadal on Sunday could be the high-profile meeting that dictates which of these two European giants advances to the semis.
Young overcame old in Genoa, where Pouille, 24, denied 34-year-old Seppi the opportunity to build on his record of comeback victories, per the Davis Cup Twitter account:
Seppi looked like a different player for much of the second half of their meeting, returning from two sets down to draw level before crashing in the clutch set.
There, Seppi contributed 15 unforced errors to Pouille's six, with the Frenchman able to summon his best when it counted and beating his Italian opponent in their first career meeting.
But Fognini later returned the favour with a comeback win over Chardy, recovering from a first-set loss and going on to break the Frenchman eight times over the final three sets en route to a 6-7(6), 6-2, 6-2, 6-3 win.
Meanwhile, Cilic was at east in front of a Croatian audience in Varazdin and sailed to a 6-2, 6-1, 6-2 thrashing of Popko, who lost out with a wild return, via Davis Cup:
The young Kazakh was more accurate in his serving but crucially failed to convert as many points from that position, per the competition's official website, leaving Cilic to swoop in and steal a lead for Croatia.
Cilic's Croat team-mate, Borna Cilic, couldn't keep up the victorious start and succumbed to Mikhail Kukushkin later on Friday, ensuring all three quarter-finals played earlier on Friday finished at one win apiece after the opening round of matches.